Glencore Xstrata promised investors on Tuesday it would slash costs, shelve risky projects and squeeze more benefits from its $46 billion takeover of mining group Xstrata, lifting its target to at least $2 billion of synergies by next year.

After falling by almost 20 percent earlier this year, copper prices have rallied over the past two months, helped by an uptick in Chinese economic activity. However, analysts warn the rebound may be short-lived.

Falling demand from China will likely cause an oversupply in the copper market by the end of this year and could weigh on prices for the metal until 2016, the CEO of copper miner Antofagasta told CNBC on Tuesday.